(a) Technical Field of the Invention
The present invention relates to an electronic power supply device for light-emitting diodes (LEDs), which is aimed to provide an electronic power supply device for LEDs to make a breakthrough for the limitations imposed to the currently available (low-power) LEDs due to restriction and stability in voltage, current and temperature in order to make the application and lighting efficiency of the (low-power) LEDs well satisfying the general requirements for regular lighting purposes; thus the present invention is provided to enhance the lighting efficiency of the low-power LEDs by offering features of control, detection, protection, and brightness adjustment and maintaining stable effect of current, voltage and temperature within the rated ranges of voltage, current, and temperature to thereby improve the performance utilization efficiency of the whole LED module and make the low-power LEDs fully exploiting the maximum performance utilization efficiency and brightness efficiency so as to effectively overcome the operation problems of high-power LEDs caused by exceeding high temperature and also to provide the low-power LEDs with new fields of application by upgrading the low-power LEDs to the primary grade of lighting application. Accordingly, the present invention provides an electronic power supply device for LEDs, which is applicable to both high-power LEDs and low-power LEDs for enhancement of brightness efficiency, performance utilization efficiency, and temperature controllability.
For high-power LEDs, their specifications are usually set on the basis of wattages, such as 1 W, 3 W and 5 W. Thus, the rated voltage and current of the high-power LEDs are high and the brightness that can be given off is correspondingly heightened. For the current technology, if heat dissipation is temporarily not taken into consideration, projects of using the high-power LEDs in primary lighting device are available. Such projects are the important concerns for the manufacturers in the related fields.
In view of the characteristics of the high-power LEDs, since they have high rated voltage and current, high radiation of thermal energy occurs. For the current development of high-power LEDs, the problem heat dissipation is always troubling the manufacturers and no feasible solution for optimum and efficient dissipation of heat is available. Thus, power consumption and thermal issue are major factors for the success of the high-power LEDs. However, these two are of a vicious circle relationship and are the factor for the failure of the high-power LEDs.
For the applications of the high-power LEDs, the most important issue is the dissipation of heat generated thereby. If the heat cannot be properly dissipated, once the temperature gets beyond the rated range of temperature, the LEDs may get burnt out or aging thereof is accelerated. This is true for both low-power and high-power LEDs. Once aging occurs, the brightness of the LEDs get seriously deteriorated, which is thus irreversibly damaged. Thus, the heat dissipation issue is the most important challenge for the manufacturers and engineers, and various proposals have been made. Such proposed thermal solutions for high-power LEDs are of two categories, the active heat dissipation mechanism and the passive heat dissipation mechanism. Other types of heat dissipation, such as liquid heat dissipation device disclosed in UP patent documents, which is applicable to bulb-shaped LED structure, is also available.
For low-power LEDs, since the rated voltage and current are low, their power consumption and heat generated are small. Currently, the low-power LEDs are mature market products, but they are still of poor brightness efficiency and the applications thereof are dependent upon the factors including constituent number of the LEDs, the voltage, the current, and the heat dissipation gap. Thus, they are not still applicable in the field of lighting.
Although the present invention is applicable to the range of high-power LEDs for realizing control, detection, protection, brightness adjustment and for being well maintained in the rated ranges of voltage, current and temperature, to provide extremely stable current, voltage and thermal effect and thus enhancing the performance utilization efficiency and maximum brightness efficiency of the whole LED module, yet incorporation with a heat dissipation mechanism for accelerating heat dissipation is preferred. For low-power LEDs, a novel and revolutionary application can be realized. First, according to the characteristics of the low-power LEDs, since the rated voltage and current are low, the power consumption and temperature are low and thus, the issues of power saving and low thermal efficiency can be alleviated and overcome. Thus, the present invention is made on the basis of the following aspects.
The first aspect of the present invention is to provide a power supply system of extremely stable voltage and current within the rated ranges of voltage and current of the LEDs (including both high-power and low-power LEDs) so that an LED module can have extremely stabilized lighting efficiency for effectively controlling the thermal issue induced.
The second aspect of the present invention is to up-push the voltage and current of LEDs within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply, so that the brightness efficiency and the temperature of the LEDs can be of optimum (maximum) level of matching within the normal operation values and temperature.
The third aspect of the present invention is to employ a photo-coupling circuit for detection the supplied current and voltage and the energy conversion efficiency within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, so that any minor variation can be effectively changed and handled to provide intelligent functional modulation capability to further realize protection of LED modules and the power supply, leading to extension of service life of both.
The fourth aspect of the present invention is to monitor the temperature of working environment (which means extremely bad and extremely hot working environment here) within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, in order to first use an effective and stable process to reduce the current and voltage for protecting the power supply device and maintaining the normal operation of the LED module and then, after the power supply dropping the voltage and current to resume the normal operation temperature, use an effective and stable process to increase the current and voltage, so that a humanized control mechanism can be realized (such changes taking place in a naked-eye invisible fashion) for protecting the LED module and extending service life thereof.
The fifth aspect of the present invention is to monitor the temperature of working environment (which means extremely bad and extremely cold working environment here) within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, in order to activate a system heating module for pre-heating the circuit device to realize protection of the LED module and extending service life thereof.
The sixth aspect of the present invention is to combine an LED brightness adjustment module to the load end, within the rated voltage and current and temperature of the LEDs (including both high-power and low-power LEDs) and under the condition of ensuring stable power supply and enhanced brightness efficiency, in order to realize stepless adjustment of brightness.
Based on the above description, the present invention provides an electronic power supply device for LEDs, which facilitates the applications of LED modules to various lighting and indication for enhancing the operation and model of LED module and this is particularly a novel way of application for low-power LEDs. Meanwhile, the present invention allows significant enhancement of brightness and efficiency of LEDs within the rated ranges of voltage, current and temperature and under the condition for realizing control, detection, protection, brightness adjustment and providing stable current and voltage and temperature effect, to thereby significantly improve brightness efficiency of LED module and effectively control and protect the power supply device and the LED module for eventually achieving the goals of power saving and extended service life.
(b) Description of the Prior Art
In the field of lighting, household lighting devices have evolved from the early stage of incandescent bulbs of high wattage to lamp tubes (fluorescent tubes) and further evolved to the energy-saving lamp tubes, such as PL tubes, energy-saving bulbs (with stabilizer). This change to the household lighting device was simply happening in a short periods of tens of years and a significant progress and innovation occurs for the lighting devices.
Recently, the era of environment conservation and development of substitute energy arrives; and the energy-saving lighting devices, which are most commonly used recently, namely the fluorescent tube, the PL tubes, and the energy-saving bulbs, are subjected to challenge for saving of power for the amount of energy consumed by these lighting devices is dependent upon the quantity thereof. A great quantity of the lighting devices certainly causes a great amount of energy consumed. Taking the fluorescent tube as an example, the power consumption for use of four 20 W fluorescent tubes can be calculated as 20 W×4=80 W. This way of calculation is also applicable to PL tubes and bulbs. Further, in the case of PL tubes and power-saving bulbs with stabilizer, the power consumption is less than the traditional lighting bulbs, but a by-product of “high temperature” is caused, which leads to additional load and/or requirement of installation of air-conditioning systems. An additional safety problem also rises for all the lighting bulbs or tubes are made of glass, which is of a potential risk of explosion and they are considered highly dangerous objects in installation, waste handling, recycling and transportation.
In view of the above problems, low-power light-emitting diodes (LEDs) provide a feasible solution and are becoming a prosperous and promising substitute for the traditional lighting devices. According to reports and articles describing the low-power LEDs as a substitute for the traditional lighting, due to the advantages of having high brightness, capability of long distance projection, high condensability, and low power consumption, the low-power LEDs are quite a solution for lighting that meets the general needs of human society and environmental conservation. The most important is the extreme saving of power that the LEDs can achieve and the availability of material and low costs for making the LEDs, which give the LEDs the most important advantages of reduced cost. Thus, the LEDs is of the most promising commercial application in the filed of lighting.
The LEDs are operated with direct current (DC) power. Thus, for the operation of the LEDs, if battery or cell based DC power supply is excluded and alternate current (AC) power mode is taken into consideration, the operation of LEDs would require conversion of the AC into DC power before the power can be supplied to the LEDs. This is the general way and construction that the application of the LEDs is taken. For example, as shown in FIGS. 1-3 of the attached drawings, conventionally, a power supply device is employed to realize power supply to the LEDs, and the known power supply device generally comprises a bridge rectifier A1, which converts 110V-220V AC into DC of 12V or 9V or 3V. Then, a capacitor A2 converts the waveform into DC pulses of positive cycles of Sine wave to thereby complete the conversion.
However, in respect of the high-power LEDs, since the output voltage and current (around 3 A) are still of high levels, for a large-sized high-power LED module, a bulky power supply device is needed to supply power of regulated voltage and stable current. On the other hand, for the LED module at a load end, since the output voltage and current are of high levels, remarkable variation of instantaneous voltage, current, resistance and temperature may occur, making the load end very unstable. Further, since the LED module is usually of a large scale and compact design, high temperature often result. For design of poor heat dissipation, high temperature would result again and the high temperature itself leads to instability of instantaneous voltage and current, which once again result influence of the LED module of the load end.
Once the voltage and current of the supplied power or the temperature caused thereby exceed the rated values specified to the LEDs, aging of the LEDs, such as deterioration of lighting performance and reduction of brightness, may occur, or even worse, the LEDs may get burnt out. Thus, application of the high-power LEDs in the field of lighting will inevitably encounter the problems associated with current, voltage and temperature. Consequently, the stability and service of lighting device using the high-power LEDs are still doubtful.
For low-power LEDs, since the output voltage and current are small, the temperature caused is low, but the lighting performance is apparently insufficient. Thus, conventionally, the operation mode of the low-power LEDs is simply making straightforward and simple conversion by using diodes before the power is employed to drive the low-power LEDs. Further, to ensure the low-power LEDs well within the rated ranges of current, voltage, and temperature, the lighting efficiency and performance of the low-power LEDs are kept low.
If the number of LEDs at the load end is significantly increased and the lighting efficiency of the low-power LEDs is enhanced and the LED module of the load end adopts a large-scale and compact design, then the required output voltage and current will be increased, and the temperature is also increased. Thus, the same old problems of the high-power LED rise again. Thus, the three factors of current, voltage, and temperature caused are the primaries that are considered in the present invention.